Speech and language based dementias (SLDs) (often referred to as primary progressive aphasias) are neurodegenerative diseases in which speech and language impairments are the most salient features of the disease and explain deficits in activities of daily living. These dementias may or may not be associated with the deposition of the protein beta-amyloid in the brain, which until recently could only be determined at postmortem. Since new treatments will likely target underlying abnormal proteins, accurate prediction of the pathology underlying the SLDs is critical. The recent development of amyloid imaging compounds now allows the in vivo detection of beta-amyloid in the brain. Unfortunately, amyloid imaging compounds are expensive and are not accessible to most medical centers throughout the United States. The objectives of the studies outlined in this proposal are to identify clinical, neuropsychological or non-amyloid imaging biomarkers that are readily available, relatively inexpensive, and non-invasive, that will allow the prediction of beta-amyloid in the brain in patients with SLDs. To accomplish this goal we will be using the amyloid imaging compound 11C Pittsburgh Compound B (PiB) as the gold standard for the detection of beta-amyloid. The methods will include detailed neurological, speech and language and neuropsychological assessments, magnetic resonance imaging, and [18-F]-fluoro-deoxy-glucose (FDG) and PiB PET scanning. Associations between PiB positive scanning and these techniques will be sought. One of the most salient features of the speech and language assessments will be the determination of the presence and severity of apraxia of speech and its association with beta-amyloid deposition. This study will be carried out at the Mayo Clinic in Rochester, MN, which evaluates a large number of patients with SLDs annually. The study also intends to recruit minorities with SLDs which are currently understudied. The methods will be performed by a team of world renowned scientists including dementia, movement disorders and speech pathology specialists, radiology researchers, a nuclear medicine scientist, neuropsychologists, and biostatisticians. The long term goal of our research is to develop a cost effective algorithmic approach to the evaluation and diagnosis of patients with SLDs.